1. Field of the Invention
This invention relates to a folding bicycle constructed in a manner foldable about a central portion of a body thereof.
2. Description of the Related Art
A bicycle 71 shown in FIG. 12 is among folding bicycles of the above-mentioned type as the related art. The bicycle 71 includes a frame 74 rotatably supporting a front wheel 2 and a rear wheel 3, a drive mechanism 6 for driving the bicycle 71, a rack 75 secured above the rear wheel 3, a steering section 77 linked to the front wheel 2, a seat section 8 secured to a central portion of the frame 74, and a kick stand 79 that allows the bicycle 71 in its extended state to stand by itself and is capable of supporting the bicycle 71 in its folded state. The frame 74 is comprised of a front fork 11 connected to the steering section 77 and having the front wheel 2 secured thereto via an axle 2a, a steering head 12 holding the front fork 11 and the steering section 77 in a rotatable manner, a down tube 13, a folding mechanism 14 for folding the bicycle 71, a rear arm 85 connected to the down tube 13 via the folding mechanism 14 and having the rear wheel 3 secured thereto via an axle 3a, a seat tube 86 extending upward from the rear arm 85, for having the seat section 8 secured thereto such that the seat section 8 can be moved vertically, a seat stay 87 connecting between the rear end portion of the rear arm 85 and the upper end portion of the seat tube 86, and a stay 88 having the rack 75 secured thereto.
The drive mechanism 6 includes a pedal-side sprocket 33 to which are attached pedals 32, 32 via respective cranks 91a, 91b, and a rear wheel-side sprocket 35 which is rotated via a sprocket chain 34 as the pedal-side sprocket 33 rotates. The steering section 77 is comprised of a stem 95 connected to an upper end of the front fork 11 within the steering head 12 and a handle bar 96 secured to the upper end of the stem 95. Further, the seat section 8 is comprised of a seat post 51 secured to the seat tube 86 such that the seat post 51 can be moved vertically therein, and a saddle 53 secured to the upper end of the seat post 51 via a saddle angle-adjusting mechanism 52.
The bicycle 71 is folded through the following procedure. First, as shown in FIG. 13, the seat post 51 is pushed down into the seat tube 86 such that it is received therein. Then, after the handle bar 96 is turned downward to a position where each of the opposite ends thereof looks as if suspended from the upper end of the stem 95, the steering section 77 in this state and the front fork 11 having the front wheel 2 secured thereto are turned around. At this time, the front wheel 2 is shifted toward the folding mechanism 14 by a distance which is twice longer than a front fork offset. Subsequently, the bicycle 71 in this state is folded by and about the folding mechanism 14 at the central portion of the bicycle 71. As a result, the front wheel 2 is positioned at the left side of the rear wheel 3 (as viewed from the rear of the bicycle 71), whereby the length of the bicycle 71 is reduced approximately by half in comparison with the whole length of the bicycle 71 in its extended state. Thereafter, by placing the front and rear wheels 2, 3 and the kick stand 79 on the ground, with the kick stand 79 kicked backward as shown in FIG. 14, the bicycle 71 in its folded state stands in a state supported by the front and rear wheels 2, 3 and the kick stand 79.
However, the above bicycle 71 suffers from the following problems: As described above, the bicycle 71 is folded by and about the folding mechanism 14 at the central portion of the bicycle 71, so that the length of the bicycle 71 is reduced approximately by half in comparison with the whole length of the bicycle 71 in its extended state. However, the distance from the axle 2a to the folding mechanism 14 and the distance from the axle 3a to the folding mechanism 14 are each longer than the radius of the front wheel 2 and that of the rear wheel 3, and hence the down tube 13 and the rear arm 85 project considerably far from the front and rear wheels 2, 3 in the folded state of the bicycle 71. If the distance between the two axles 2a, 3a is reduced so as to solve the above problem by reducing the distances between the respective axles 2a 3a and the folding mechanism 14, running stability of the bicycle 71 is degraded due to the reduction of the distance between the axles 2a, 3a. Since it is thus difficult to reduce the distance from the axles 2a, 3a of the respective wheels 2, 3 to the folding mechanism 14 in the folded state while maintaining the running stability of the bicycle 71 in the extended state, reduction of the size of the bicycle 71 in its folded state (hereinafter also referred to as xe2x80x9cthe folded bicycle 71xe2x80x9d) is difficult.
Another problem occurs with the folded bicycle 71 when it is carried. If a user tries to move the folded bicycle 71 by rotating the wheels 2, 3 on the ground, rotation of the rear wheel 3 causes rotation of the rear wheel-side sprocket 35, whereby the pedal-side sprocket 33 is rotated via the sprocket chain 34. As a result, the pedal 32 attached to the crank 91a is brought into abutment with the front wheel 2 or the down tube 13. This abutment inhibits the rotation of the rear wheel-side sprocket 35, and hence it becomes impossible to rotate the rear wheel 3. Consequently, the user has to carry the folded bicycle 71 e.g. by holding the seat tube 86 by hand and lifting the whole bicycle 71.
Still another problem is as follows: In the bicycle 71, the handle bar 96 is turned with respect to the stem 95 for reduction of the size of the bicycle 71 in its folded state. However, even when the handle bar 96 is turned downward, the length from the steering head 12 to the upper end of the stem 95 is not reduced, and, what is more, the opposite ends of the handle bar 96 largely project leftward and rightward, respectively, from the folded bicycle 71. This also makes it difficult to reduce the size of the bicycle 71 in its folded state. Further, the pedals 32, 32 also largely project leftward and rightward, respectively, from the folded bicycle 71, which also makes it difficult to reduce the size of the folded bicycle 71.
Moreover, as shown in FIG. 15, when the bicycle 71 is folded, the front wheel 2 and the rear wheel 3 are not in a state held in parallel with each other. Therefore, in moving forward or backward the folded bicycle 71 with the wheels 2, 3 placed on the ground, once the parallelism of the front and rear wheels 2, 3 is lost, the state of the two wheels more pronouncedly tends to go further away from parallelism. For this reason, when the user tries to move the folded bicycle 71 straight in the direction of reverse rotation of the rear wheel 3 e.g. by pushing the seat tube 86, the resistance to rotation of the front wheel 2 is increased, which makes it difficult to carry the bicycle 71 in a state of the wheels 2, 3 being on the ground.
In addition, there is another problem that when the bicycle 71 is folded, the user has to carry baggage which was placed on the rack 75 during running of the bicycle 71, apart from the bicycle 71. More specifically, in the state of the bicycle 71 being folded, the rack 75 is inclined at a large angle with respect to the ground GL as shown in FIG. 14, so that if the baggage is left on the rack 75, the baggage can fall off the rack 75 due to its own weight. Therefore, it is hard to carry the bicycle 71 with the baggage placed on the rack 75, and hence the user has to carry the bicycle 71 by one hand while carrying the baggage by the other hand, which is very troublesome and laborious.
It is an object of the invention to provide a folding bicycle that is reduced in size in its folded state while maintaining the running stability in its extended state and easy to carry in its folded state.
It is another object of the invention to provide a folding bicycle that can be carried with baggage loaded thereon.
To attain the above objects, the present invention provides a folding bicycle including a front wheel, a rear wheel having an axle, a rear wheel-side sprocket connected to the rear wheel, a sprocket chain for being engaged with the rear wheel-side sprocket, and a folding mechanism permitting the folding bicycle in an extended state to be folded at an intermediate region between the front wheel and the rear wheel, wherein the folding bicycle is folded by the folding mechanism such that the front wheel is brought to a position at one side of the rear wheel.
The folding bicycle according to the invention is characterized by comprising an axle shift mechanism permitting the axle of the rear wheel to be shifted to a position toward the intermediate region, and a chain-holding mechanism that holds the sprocket chain at a predetermined position when the axle is shifted to the position toward the intermediate region by the axle shift mechanism, to thereby release engagement between the rear wheel-side sprocket and the sprocket chain.
According to this folding bicycle, since the bicycle is provided with the axle shift mechanism that permits an axle of the rear wheel to be shifted toward the intermediate region, it is possible to increase the distance between the two axles in the extended state of the bicycle, thereby securing the running stability of the bicycle, and at the same time it is possible to reduce the distance between the two axles in the folded state of the bicycle, thereby reducing the size of the folded bicycle. Further, in the folded state of the bicycle, the chain-holding mechanism holds the sprocket chain at the predetermined position when the axle is shifted toward the intermediate region by the axle shift mechanism, thereby releasing engagement between the rear wheel-side sprocket and the sprocket chain, so that it is possible to prevent the rear wheel-side sprocket from being rotated with rotation of the rear wheel, thereby allowing the folding bicycle to be moved by rotation of the wheels.
Preferably, the folding bicycle includes a front wheel-securing mechanism that rotatably secures the front wheel in a folded state of the folding bicycle, such that lines of intersection where a plane of rotation of the front wheel defined as an imaginary geometrical plane which contains a diameter of the front wheel and to which a rotational axis of the front wheel is perpendicular, and a plane of rotation of the rear wheel defined as an imaginary geometrical plane which contains a diameter of the rear wheel and to which a rotational axis of the rear wheel is perpendicular intersect with a ground plane defined as an imaginary geometrical plane corresponding to an arbitrary surface on which the front wheel and the rear wheel are supported are substantially parallel to each other.
According to this preferred embodiment, the front wheel-securing mechanism rotatably secures the front wheel in the folded state of the bicycle, such that lines of intersection where planes of rotation of the respective front and rear wheels intersect with the ground plane are substantially parallel to each other, so that when the folding bicycle in the folded state is moved by rotation of the wheels, the front and rear wheels rotate smoothly, thereby making it easy to move the folding bicycle.
Preferably, the folding bicycle includes an auxiliary wheel arranged in the vicinity of the folding mechanism such that the auxiliary wheel can be placed on a ground together with the front wheel and the rear wheel in the folded state of the folding bicycle, a rack arranged above the rear wheel, and a rack retainer mechanism that holds the rack generally horizontal with respect to a ground plane on which the front and rear wheels are placed, both in the extended state and in a folded state of the folding bicycle.
According to this preferred embodiment, by holding the rack horizontal by means of the rack retainer mechanism, it is possible to move the bicycle in the folded state with baggage placed on the rack by rotation of the front and rear wheels and the auxiliary wheel. Thus, the bicycle in the folded state can be used as a cart.
Preferably, the folding bicycle includes a kick stand arranged in the vicinity of the folding mechanism such that the kick stand can support the folding bicycle in a folded state thereof when the kick stand is in a predetermined position, and a seat post, and when the front wheel, the rear wheel, and the kick stand are placed on a ground in the folded state of the folding bicycle, the seat post is generally perpendicular to a plane of the ground.
According to this preferred embodiment, when the bicycle in the folded state is supported by the kick stand, the seat post is generally perpendicular to the ground plane, so that simply by adjusting a saddle such that it is held in a horizontal position with respect to the ground plane, it is possible to use the folded bicycle as a chair.
Preferably, the folding bicycle includes a pair of pedals, a pair of pedal cranks connected to the pedals, respectively, one of the pair of pedals projecting from a corresponding one of the pair of pedal cranks in a direction away from the one side of the rear wheel in a folded state of the folding bicycle, and a crank-turning mechanism that permits the one of the pair of pedal cranks to be turned in a manner such that the one of the pair of pedals projects toward the one side of the rear wheel.
According to this preferred embodiment, the crank-turning mechanism makes it possible to turn one of the pedal cranks such that the left and right pedals project in the same direction. Therefore, it is possible to reduce the width of the bicycle in the folded state, whereby the size of the folding bicycle can be further reduced in its folded state.
Preferably, the folding bicycle includes a handle system having a telescopic column portion, and an extended portion connected to an upper end of the telescopic column portion such that the extended portion can be fixed at a desired stem angle and that the extended portion can be rotated about an axis extending in a direction of extension of the extended portion.
According to this preferred embodiment, the bicycle is provided with the telescopically and rotatable handle system. Therefore, it is possible to make the bicycle in its folded state more compact, whereby the size of the folding bicycle can be reduced in its folded state.